Device for heating non-metallic material



Oct. 7, 1969 H. A. PUSCHNER 3,471,671

DEVICE FOR HEATING NON-METALLIC MATERIAL Filed May 9. 1966 United States Patent 3,471,671 DEVICE FOR HEATING NON-METALLIC MATERIAL Herbert August Piischner, 175 Osterholzer, Heerstrasse, 28 Bremen, Germany Filed May 9, 1966, Ser. No. 548,587 Int. Cl. Hb 9/06 US. Cl. 219-1055 6 Claims ABSTRACT OF THE DISCLOSURE A microwave oven has a rotary converter comprising a circular disc having a number of vanes mounted about its periphery. A stream of air enters the oven and impinges upon the vanes to rotate the disc. Microwave energy enters the oven through an inlet coupling with the disc being rotatably mounted about the axis of and adjacent to the inlet coupling.

The present invention relates to a device for heating non-metallic materials, more particularly foodstuffs, by microwave energy with a cavity resonator as heating chamber, in which a rotating oscillation type converter is provided.

In the known devices of this kind, the oscillation type converter is driven by a motor arranged outside the heating chamber. Accordingly, a special drive motor has to be provided.

The present invention is based on the consideration that the drive of the wave converter requires only very little energy. Accordingly, it is an object of the invention to provide a device for heating non-metallic materials by microwave energy, comprising a heating chamber in the form of a cavity resonator, a rotating oscillator type converter being arranged in the cavity resonator, said converter having means establishing rotation thereof when impacted by an air stream, means being provided for directing an air stream onto said rotation establishing means, whereby to effect rotation of the converter. The driving air stream can simultaneously serve for carrying off steam in the heating chamber and the air pump or other air stream generator can also be used for producing the cooling air stream for the cooling device of the microwave generator. By these measures not only is an additional driving motor saved, but the necessity of guiding the driving shaft through the wall of the heating chamber, which could lead to disturbances at high frequencies, is avoided.

The above and other objects and advantages of the invention will be clear from the following description given with reference to the accompanying drawing which is given by way of example and which diagrammatically illustrates a device according to the invention, for heating foodstuffs by microwave energy.

The illustrated device comprises a heating chamber 1 in which the foodstuff to be heated is placed. The heating chamber has a door 2 at its front side, the central part of which is for-med by a perforated plate 3. A coaxial inlet coupling 4 is provided centrically in the cover of the heating chamber, through which the microwave energy, which is provided by a generator, not illustrated in the drawing, is coupled into the heating chamber acting as a cavity resonator. The cavity resonator is for this purpose provided with metallic walls and is for example in the form of a light metal casting.

In order to achieve a uniform field distributor, an oscillation type converter 5 which rotates coaxially to the inlet coupling 4 is provided, which acts as a field stirring or whirling device. It consists of a circular plate which is provided with vanes 6 at its periphery for driving, which are impelled by an air stream 7. This air stream passes into the heating chamber through a pipe 8 tangential to the converter 5 and is obtained from a fan 9.

The air stream 7 simultaneously serves for ventilating the heating chamber and causes a satisfactory vapour removal through the perforated plate 3 of the door 2. The strength of the air stream 7 can be adapted to the conditions in each case, since the speed of rotation of the converter 5 does not have to have any predetermined value.

The main air stream of the fan 9 passes through a circulation line 10, 11 in which a heat exchanger 12 for cooling down the cooling water for the microwave generator is inserted.

I claim:

1. Microwave heating apparatus comprising,

means defining a heating chamber in the form of a cavity resonator,

means defining an inlet coupling for transmitting microwave energy into said chamber, a rotary converter means for establishing a substantially uniform field distribution within said chamber,

means for rotatably mounting said rotary converter means about the axis of and adjacent to said inlet coupling,

said rotary converter means comprising a generally circular disc having a plurality of vanes mounted about its periphery,

means for directing a stream of air into said chamber upon said vanes to rotate said disc,

said means defining a heating chamber being formed with openings for releasing air from said chamber.

2. Microwave heating apparatus in accordance with claim 1 wherein said inlet coupling and said rotary converter means are at the top of said chamber, said means for directing comprises an air outlet at the rear of said chamber and said openings are formed in the front of said chamber.

3. A device for heating non-metallic materials by microwave energy, comprising a heating chamber in the form of a cavity resonator, a rotating oscillation type converter being arranged in and surrounded by the cavity resonator, said converter having means establishing rotation thereof when impacted by an air stream means being provided for directing an air stream onto said rotation establishing means whereby to efifect rotation of the converter.

4. A device according to claim 3, wherein the rotation establishing means comprise vanes.

5. A device according to claim 3, wherein air outlet means are provided for the cavity resonator, whereby the said air stream serves for removal of vapour from the cavity resonator.

6. A device according to claim 3, wherein said air stream directing means comprise an air stream generator arranged in a circulation path through a heat exchanger, said heat exchanger being arranged for cooling down cooling water for a microwave generator supplying the said microwave energy.

References Cited UNITED STATES PATENTS 2,956,144 10/1960 Woodman 219-1055 3,081,392 3/1963 Warner 219-1055 3,091,172 5/1963 Wildemann 219-1055 X 3,211,880 10/1965 Johnson 219-1055 3,281,568 10/1966 Haagensen 219-1055 3,323,020 5/1967 Lenart et a1. 219-1055 X 2,748,239 5/1956 Long et al. 219-1055 FOREIGN PATENTS 1,476,179 4/ 1967 France.

JOSEPH V. TRUHE, Primary Examiner L. H. BENDER, Assistant Examiner 

